Ostomy appliances of so-called one-piece and two-piece constructions are commonly provided with adhesive faceplates for adhesively securing the appliances to the peristomal skin surfaces of wearers. For example, patent GB 2 290 974 discloses the faceplate of a two-piece appliance having a coupling ring 12 (to which a collection pouch or bag is to be removably coupled), an annular wafer 18 of medical grade adhesive, and a moldable mass 24 of non-memory putty-like adhesive 24, which may be hydrocolloid or hydrogel based, having a central hole therein. The moldable adhesive mass 24 has a consistency allowing it to be manipulated and pressed into position around a stoma with the fingers. An annular patch 22 of microporous adhesive tape or foam backs the wafer, and the bodyside surface of the wafer is covered with a removable release sheet 26.
U.S. Pat. No. 5,496,296 also discloses an ostomy faceplate having plural adhesives, one which contacts peristomal skin surfaces and performs a load-bearing function, and another which is soft, moldable and extrudable. The moldable adhesive surrounds and contacts the stoma and performs a gasketing or sealing function with respect to the stoma. The latter adhesive is capable of being molded by finger pressure into direct contact with the stoma following initial adhesive attachment of the faceplate to the wearer's body. In attaching a two-piece appliance, the molding step would preferably occur before the pouch is coupled to the faceplate, whereas the procedure with a one-piece appliance might require at least part of the molding step to occur by finger pressure applied through the front or distal wall of the pouch after the appliance has been adhered to the body.
Despite their advantages in forming fluid-tight gaskets or seals against a stoma, such putty-like moldable adhesives have been reported as lacking cohesive strength and being subject to cold flow. Thus, the point has been made that the required lack of memory of a moldable adhesive such as disclosed in the aforementioned British patent 2 290 974 results in the disadvantage that the adhesive may creep or flow under ambient conditions or during use. That problem has been addressed by chemically or physically crosslinking one or more of the components of the non-hydrocolloid portion of such an adhesive, but the incorporation of crosslinks then may have the disadvantage of introducing significant elasticity into the adhesive (see published application US 2007/0185464 A1).
In U.S. Pat. No. 6,332,879, elasticity or recoverability is purported to be advantageous in a hydrocolloid adhesive wafer having a sealing member with “balanced” plastic and elastic properties because it allows temporary enlarging of the hole through the wafer, to adapt it for accommodating a stoma, by everting or rolling the rim of the hole upon itself. After having been placed over and around the stoma, the elasticity of the wafer allows it to recover essentially to its original form to fit snugly about the stoma. In one embodiment, the sealing member is provided with grooves encircling a central stoma receiving opening for enlargement of the stoma receiving opening by lateral displacement outwardly of the rim compressing the grooves after which the sealing member, because of its elastic properties, expands to provide a snug fit to the stoma.
In contrast to a hydrocolloid adhesive having balanced plastic and elastic properties, one that may be regarded as being only moldable is essentially devoid of memory and elastic recoverability. While some strain recovering properties may exist, they are too limited to be of significance in affecting the putty-like non-memory characteristics of such a moldable adhesive. Thus, publication WO 2007/076862 discloses a layered adhesive construct designed for skin contact in which the construct has two (or more) layers of hydrocolloid adhesive. Only the first layer is identified as being of a moldable adhesive and, by definition, its Strain Recovery is required to be below 45%, preferably below 35%, when measured as described in the disclosure. By contrast, the hydrocolloid adhesive of the second layer, which is not identified as being moldable, is required to have a Strain Recovery above 55%.
Other patents and publications illustrative of the state of the art are: U.S. Pat. No. 6,840,925; US 2006/0184145; U.S. Pat. No. 6,764,474; GB 2 277 031; WO 2006/038025; U.S. Pat. Nos. 6,652,496; 6,312,415; U.S. Pat. No. 5,074,852; EP 0 888 760; U.S. Pat. No. 6,509,391; EP 0 991,382; US 2005/054997; U.S. Pat. No. 3,683,918; U.S. Pat. No. 7,172,581; U.S. Pat. No. 6,589,222; U.S. Pat. No. 5,147,340; U.S. Pat. No. 3,667,469; WO 2007/076682; EP 1 164 983.